We propose to develop and maintain a Data Coordinating Center (DCC) to support the Adult to Adult Living Donor Liver Transplantation (AALDLT) Cohort Study including a Specimen Core Facility. The proposed AALDLT DCC will be comprised of multidisciplinary expertise in liver transplantation, biostatistics, epidemiology, clinical trials, and data management. We will develop a secure, integrated Internet-based data entry and data management system to support data and specimen acquisition. The AALDLT DCC will coordinate the design and implementation of the AALDLT cohort study and clinical protocols and will provide support in the relevant content areas to the Steering Committee and the NIDDK in its effort to accomplish the primary goal of conducting a longitudinal study of the recipients and donor outcomes in AALDLT. The DCC will accomplish the foregoing goals through the implementation of the following specific aims: 1. Design, organize, implement and coordinate a secure electronic, centralized web-based distributed data entry system for the participating transplant centers (TCs) 2. Establish a secure data management and archival system for the AALDLT cohort study, clinical protocols and substudies 3. Develop comprehensive, valid data collection instruments4. Establish a high standard, quality-assured central repository for biological specimens acquired from AALDLT donors, recipients, and controls5. Perform methodologically rigorous analyses of AALDLT data 6. Facilitate the presentation, dissemination and publication of the results of the AALDLT study. 7. Organize, schedule and manage the meetings, conferencing and communication of the Steering Committees, subcommittees, the DSMB and the central laboratories involved in the AALDLT study. 8. Provide timely and effective communication among the NIDDK project officer and project scientists, DCC, and participating TCs regarding all aspects of the AALDLT study to ensure the fulfillment of the programs scientific goals.